I've had exactly the same issue at work James, i take it yours is the 1.9 not the 2.0, I ended up replacing the air flow metre, egr, glow plugs, both relays, and even the lifter pump in the tank. When it ran it sounded a bit lumpy(very slightly) checked the timing and found the belt had stretched(half a tooth) so replaced the belt and spot on started on the button.........

2 weeks later same issue and it ended up being the common rail